vboot_reference: Support MTD devices in dump_kernel_config

This CL implements a read function that works with MTD devices in
dump_kernel_config.

BUG=chromium:457862
BRANCH=none
TEST=make runtests
TEST=try on storm_nand

Change-Id: Id784d422de64e7918b163005c0b426d727d2115e
Reviewed-on: https://chromium-review.googlesource.com/249271
Reviewed-by: Nam Nguyen <namnguyen@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Trybot-Ready: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
2 files changed